package com.wohaibao.sumecom.util;

import java.io.UnsupportedEncodingException;  

/** 
* @author  
* @date 
*/  
public class Base64Utils  
{  
   private static char[] base64EncodeChars = new char[]  
   { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',  
           'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',  
           'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',  
           '6', '7', '8', '9', '+', '/' };  
   private static byte[] base64DecodeChars = new byte[]  
   { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
           -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,  
           54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,  
           12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,  
           30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,  
           -1, -1, -1 };  
 
   /** 
    * 加密 
    *  
    * @param data 
    * @return 
    */  
   public static String encode(byte[] data)  
   {  
       StringBuffer sb = new StringBuffer();  
       int len = data.length;  
       int i = 0;  
       int b1, b2, b3;  
       while (i < len)  
       {  
           b1 = data[i++] & 0xff;  
           if (i == len)  
           {  
               sb.append(base64EncodeChars[b1 >>> 2]);  
               sb.append(base64EncodeChars[(b1 & 0x3) << 4]);  
               sb.append("==");  
               break;  
           }  
           b2 = data[i++] & 0xff;  
           if (i == len)  
           {  
               sb.append(base64EncodeChars[b1 >>> 2]);  
               sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
               sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);  
               sb.append("=");  
               break;  
           }  
           b3 = data[i++] & 0xff;  
           sb.append(base64EncodeChars[b1 >>> 2]);  
           sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
           sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);  
           sb.append(base64EncodeChars[b3 & 0x3f]);  
       }  
       return sb.toString();  
   }  
 
   /** 
    * 解密 
    *  
    * @param str 
    * @return 
    */  
   public static byte[] decode(String str)  
   {  
       try  
       {  
           return decodePrivate(str);  
       } catch (UnsupportedEncodingException e)  
       {  
           e.printStackTrace();  
       }  
       return new byte[]  
       {};  
   }  
 
   private static byte[] decodePrivate(String str) throws UnsupportedEncodingException  
   {  
       StringBuffer sb = new StringBuffer();  
       byte[] data = null;  
       data = str.getBytes("US-ASCII");  
       int len = data.length;  
       int i = 0;  
       int b1, b2, b3, b4;  
       while (i < len)  
       {  
 
           do  
           {  
               b1 = base64DecodeChars[data[i++]];  
           } while (i < len && b1 == -1);  
           if (b1 == -1)  
               break;  
 
           do  
           {  
               b2 = base64DecodeChars[data[i++]];  
           } while (i < len && b2 == -1);  
           if (b2 == -1)  
               break;  
           sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  
 
           do  
           {  
               b3 = data[i++];  
               if (b3 == 61)  
                   return sb.toString().getBytes("iso8859-1");  
               b3 = base64DecodeChars[b3];  
           } while (i < len && b3 == -1);  
           if (b3 == -1)  
               break;  
           sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  
 
           do  
           {  
               b4 = data[i++];  
               if (b4 == 61)  
                   return sb.toString().getBytes("iso8859-1");  
               b4 = base64DecodeChars[b4];  
           } while (i < len && b4 == -1);  
           if (b4 == -1)  
               break;  
           sb.append((char) (((b3 & 0x03) << 6) | b4));  
       }  
       return sb.toString().getBytes("iso8859-1");  
   }  
 
} 
